How to hard reset a HPLJ2200D printer

I have an HPLJ 2200D printer with internal Jetdirect 610N ethernet card. Suddenly when I power on the printer the top two status lights cycle through about 20-30 times then remain lit indicating some error and the printer is unusable. Has anyone else experienced this problem?

If I take out the Jetdirect card it powers up fine and I can print via parallel connection.

Anyone know what this error means? Whether it is indicative of a bad JetDirect card or a damaged slot on the printer? I know a hard reset of the printer involves holding down one of the buttons (or a combo) upon power up but I’m looking for the correct sequence and exact meaning of the error code.

Thanks!